Object-lifetime suggestions for longtime running Windows-Service

Hi all.
I am implementing an Windows Service thats access (via EntLib DAAB) an MS SQL Server all 15-30seconds. Each access will performe multiple commands. The commands are a set of 5-10 commands, naturally the parameters changes by every run.

or
B) Create every command at first use and then reuse it?
if (com == null) com = _db.GetSqlStringCommand(SQL));
_db.Execute....(com);
...

Is it in case B) necessary to call Database.ClearParameterCache() before parameter-values are set?
Only for the records: the Database-object _db will be created at OnStart() and will be destroyed at OnStop().